General Access To Data and Products
HOW TO DOWNLOAD DATA AND PRODUCTS USING HTTP

NOTICE TO FTP USERS

This is an open service for general use

DO NOT access these servers with programs/scripts that are:

too repetitive a login over time ( know frequency data changes ),
opening up multiple sessions to access the same data products

using the FTP "ls" (list command) during each returning session
as they will significantly reduce server response for everyone and severly impact the
access by all users. DO NOT DO THIS!

ACCESS Controls that are established for this service are:

No more than 20 concurrent sessions are allowed per customer,
30 min duration limit per download (don't use slow connections),
Session will drop after 5 minutes idle to permit others to access.

No persistent session in excess of 45 minutes (txt), 3 hours (bin)

The majority of our human readable warnings, forecasts and observations are downloadable
for screen viewing using standard web browsers. The information is provided on three major
data providing services. The NWS home page at weather.gov provides access to icon and graphical rendered forms of
original NWS warnings and forecast products from every forecast office. This site is the
main portal for linking to other web sites within the NWS. By virtue of you viewing this page, you are on the home page web site and have access to a large amount of NWS documentation on NWS services, practices, meteorological procesedures, and standards of operations.

Another major service is weather.noaa.gov - named the Internet Weather Source and abbreviated
as IWS. This service provides
tailored composite forecast products by specific forecast area or county warning area and
also provides METAR site observations in a decoded form by full site name. This site has
links to facsimile charts for viewing on the PC browser.

The third server URL is iwin.nws.noaa.gov which operates the Interactive Weather Information Network,
abbreviated as IWIN. This service provides the original warnings and forecasts
as generated by the forecast office. No attempt is made to separate the issued product by
forecasted geographical/zone area.

All three of these services contain only current products and observations. They do not
store archived data and products. The site pages also link to other servers that maintain
extensive product data sets and observational data files for FTP access.

A new addition to the NWS web service is the NEXRAD composite images for browser viewing. These products are also available from web
server located at NWS forecast office across the United States. Each NWS Regional Headquarters operates Web
sites that hold the product images of their regional area NEXRAD sites.

There is a "help guide" that can aid you
in establishing the procedures you should use for retrieving data and forecast products
from our file servers using the FTP protocol. This help guide addresses both the standard
directory and file name practices used by the Gateway servers listed below and the parsed
"individual data and forecast products" processed for our own use.

The structure of the data and products on the server is a flat ASCII file for
extraction by scientific meteorological research groups and others interested
in these data sets. The various files contain collections of hydrometeorological forecast
products or observational data generated in WMO message format; as well as, other files
which contain major computer model data fields NOT generated in WMO message format. Files
are created at specific time intervals and all data available in the telecommunications
switching system at file creation time are included in each file.

About the Server Directory Structure and File Content Structure

Please review our Directory & File Name
Standards pages for details and how file contents are structured to help in reading the
contents and be able to parse out the messages through automated means.

All file contents (except for some model data set files) are collective groups
of WMO messages. All meteorological data are coded in WMO standard code forms which are
documented by WMO Manual 306. The model data set
files having contents with no WMO abbreviated headings are all in GRIB or BUFR code
format.